C57BL/6J mice elicited IL-6 associated inflammatory response to A/Mexico/4108/2009 (H1N1pdm) infection.

<p>Global gene expression profiling in lungs of C57BL/6J mice infected intranasally with 10⁵ EID₅₀ A/Mexico/4108/2009 (H1N1pdm). Probes for significantly differentially expressed genes were subjected to one-way hierarchical clustering analysis (Pearson’s correlation). The most significant gene networks (Inflammatory Response, Cell Growth and Metabolism) or most prominent represented canonical pathways (IL-1 and IL-6-mediated Inflammation, Interferon Response), as determined by IPA, are indicated for each cluster (A). Expression data of genes associated with IL-6 signalling, as determined by IPA, profiled over the course of infection (B_i). Visual representation of IL-6 signalling pathway, as represented by IPA, at day 3 pi. Overlaid colors represent gene regulation status; upregulated genes are red, downregulated genes are blue. Color intensity correlates with the magnitude of change in gene expression (B_ii). Gene expression data validation by qRT-PCR for <i>Il6</i>, IL-6 signalling genes <i>Stat3</i> and <i>Il6ra</i>, and IL-6 response genes <i>Orm2</i>, <i>Saa3</i>, <i>Saa4</i>, <i>Socs1</i>, and <i>Socs3</i>. Results are expressed as fold changes over expression in non-infected controls. Reported values for each time point are the average of three samples with +1 standard deviation indicated by vertical error bars. N.I. indicates non-infected controls. The two-tailed, two-sample unequal variances Student’s t-test was used to ascertain significance (p-value <0.05 = *, p-value <0.01 = **) (C).</p

Severe A/Mexico/4108/2009 (H1N1pdm) infection triggered increased IL-6 expression in C57BL/6J, BALB/cJ, and B6129SF2/J mice.

<p>Survival curves for C57BL/6J (closed squares), BALB/cJ (grey squares), and B6129SF2/J (open squares) mice infected intranasally with 10⁴ EID₅₀ A/Mexico/4108/2009 (H1N1pdm). n = 11 for all three groups. The logrank test (α = 0.05) was used to ascertain significance in differences in survival (A_i) <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0038214#pone.0038214-Bland1" target="_blank">[43]</a>. Average weight curve for C57BL/6J (closed diamonds), BALB/cJ (grey diamonds), and B6129SF2/J (open diamonds) mice. Vertical error bars indicate ±1 standard deviation. n = 17 for all groups. Asterisks below the curves indicate significant difference between C57BL/6J weights and BALB/cJ weights, asterisks above the curves indicate significant difference between C57BL/6J weights and B6129SF2/J weights. No significant differences between BALB/cJ and B6129SF2/J weights (A_ii). Viral load in lung homogenates collected at days 0 and 3 pi. n = 3 for all groups. Infection of Madin-Darby Canine Kidney cells was employed to measure viral titers. The assay had a limit of detection of 10^1.75 TCID₅₀/g of lung tissue, indicated by the dashed line. Vertical error bars indicate +1 standard deviation (A_iii). <i>Il6</i> mRNA expression profiling in lung homogenates by qRT-PCR. Results are expressed as fold changes over expression in uninfected day 0 pi controls. n = 3 for each group. Vertical error bars indicate +1 standard deviation. (B). IL-6 expression levels in serum and lung homogenates. n = 3 for each group. Vertical error bars indicate +1 standard deviation (C_i&ii). The two-tailed, two-sample unequal variances Student’s t-test was used to ascertain significance (p-value <0.05 = *, p-value <0.01 = **, p-value <0.001 = ***).</p